The present invention relates to isolator pads for motor vehicle leaf springs, and more particularly, to a plastic isolator pad for supporting the outboard ends of a transverse mounted composite mono-leaf spring.
Composite leaf springs offer both weight and space savings over conventional coil and metal leaf spring designs used in motor vehicle suspension systems although, the most significant advantage of the composite spring is in the reduction of weight. In most applications, at least a 60% weight reduction is realized. Additionally, laboratory fatigue tests have shown that composite leaf springs are up to five times more durable than conventional multi-leaf steel springs. Down time due to spring problems is virtually eliminated with composite leaf springs.
One of the more popular composite leaf spring designs is manufactured by the Inland Division of General Motors Corporation (GM). This monoleaf spring design is made from a composite glass fiber/epoxy resin which is formed and cured to provide sufficient strength and flexibility to suspend a motor vehicle. GM has employed such springs in the suspension systems of many of their automobile lines. One particular application of this spring is in the independent rear suspension system of GM""s W-body automobile line produced between 1988 and 1997. In this application, a single composite monoleaf spring is mounted transverse to the vehicle""s frame beneath a rear suspension cross member and supports at each of its outboard ends the lower end of a rear wheel spindle. Each spindle is pivotally connected to the rear suspension cross member by parallel spindle rods. The composite spring is mounted to the suspension cross member at two points spaced along the spring length. To isolate suspension loads, each outboard end of the composite spring rests on a rubber pad or isolator disposed in a pocket area of the corresponding wheel spindle.
Rubber spring isolator devices are generally satisfactory when the vehicle is new, however, over time the isolators wear out, tear, and eventually fall out of the pocket areas of the wheel spindles. As a result, noise occurs as the suspension pivots up and down to permit the rear wheels of the vehicle to absorb bumps and other imperfections in the road surface. This noise is caused by the outboard ends of the spring contacting the metal areas of the spindle pocket area. This spring-to-metal contact can crack and break the spring. Moreover, severe deterioration or loss of the rubber isolators can cause a lowering of the rear suspension height which in turn can result in bending and breakage of the spindle rods.
Accordingly, a need exist for a more durable isolator for the outboard ends of transverse mounted leaf springs.
A plastic isolator pad comprising a top wall and opposing side walls depending from the top wall. The isolator pad is typically used for supporting an outboard end of a leaf spring.
One aspect of the invention includes a plurality of webs which extend from a bottom surface of the top wall.
Another aspect of invention includes a plurality of stiffeners which extend between the webs.
Still another aspect of the invention includes opposing ear-like projections which extend laterally from the top wall.
A further aspect of the invention includes a motor vehicle wheel suspension, comprising a vehicle frame, a leaf spring arranged transverse to the vehicle frame, a wheel spindle pivotally connected to the vehicle frame, the spring supporting at an outboard end thereof the spindle, and a plastic isolator pad mounted on a portion of the spindle, the outboard end of the spring resting on the isolator pad.